大尺度边坡岩体开裂解体破坏规律试验研究

Experimental study on failure law of cracking and disintegration of rock mass in large-scale slope

边坡岩体失稳破坏要经历开裂、贯通、解体、滑移全过程,捕捉每个环节表层变形和深部滑面力学变化规律及特征,是探索滑坡监测预警准则的关键。本文采用恒阻大变形锚索(NPR)深部滑动力自动监测系统和地表位移监测系统,在南芬露天铁矿采场下盘开展了人工开挖诱发滑坡的现场试验,目的是探索滑坡发生前后,边坡岩体开裂解体破坏和深部滑动力的变化规律和时间效应。试验结果显示:在人工开挖扰动作用下,边坡岩体表层出现裂缝的时间要滞后于深部滑动力突变时间,即当滑动力突降4 h后,边坡表层岩体初始开裂6 mm(长200 cm);当滑动力突降96 h后,表层岩体裂缝宽度达到74 mm(长1 306 cm);当滑动力突降168 h后,边坡完全崩解滑移。证明该类型边坡从深部力学失衡到表层解体破坏,至少需要7 d时间。这一成果为该地区滑动力监测预警准则建立提供科学依据。

The process of instability and failure of slope rock mass include cracking,through,disintegration,slipping. But capturing the variation and characteristics of surface deformation and deep sliding surface mechanical in each session is the key to explore the landslide monitoring and early warning guidelines. In this paper,'Constant Resistance Large Deformation Cable( NPR) deep sliding force automatic monitoring system and surface displacement monitoring system'has been applied in Nanfen open-pit iron mine stope footwall to carry out field physical simulation experiment of landslide induced by artificial excavation. It aims to explore the disintegration of slope rock mass crack damage and the variation and time effects of deep sliding force before and after the landslide. The results show that due to the effect of artificial excavation disturbance,the time of slope rock mass surface cracks is lagging behind the deep sliding force mutation time; that is,when the sliding force fell sharply after 4 h,the slope surface rock mass initial cracking was 6 mm( length 200 cm); when the sliding force fell sharply after 96 h,the surface rock mass crack width was 74 mm( length 1 306 cm); when the sliding force fell sharply after 168 h,the sliding slope collapsed completely. It proved that the duration of this type of slope from the deep mechanical imbalance to the failure of slope surface disintegration is at least 7days,and also the results provide a scientific basis for the establishment of monitoring and early warning rule of sliding force in this region.